Convert array, string. A string array can be converted into a string. This helps store many values in a single database field. There are several ways of combining the array of strings. One way uses the string.Join method. Other ways use iteration in a loop.

Example. This example program has an array of five strings. It defines two methods that will convert that string array into a single string. In some cases, the first method is best, as it lets you check the strings before adding them together.

The Program class defines a Main entry point first. It initializes a string array with five values. It then calls the two Conversion methods defined later in the program text. Finally, it prints the output of those methods.

ConvertStringArrayToString uses an internal StringBuilder to convert the array to a string. This technique is ideal when you need to loop over your string array before adding the elements.

Tip: You can actually test each individual string for some condition before appending it.

The StringBuilder class in the base class library is ideal for appending strings in loops such as in the ConvertStringArrayToString method. It prevents many string copies from happening, and should be used in most loops.

ConvertStringArrayToStringJoin uses the string.Join static method to convert the array to a string. This is sometimes faster than StringBuilder, and also results in shorter code. However, you cannot do any setup code before calling it.

Join is defined on the string type, aliased to the System.String type in the base class library. You do not call the Join method on an actual string instance or an actual array instance. Instead, you can always type "string.Join".

Static. The two Convert methods shown are static—they do not save state. For this reason, you can place them in a static class. If you specify the separator in your code, they probably will be program-specific, which limits their reusability.

Summary. We converted string arrays into strings. You can use the StringBuilder class or the static string.Join method. We noted many other common tasks and solutions with converting strings, string arrays and char arrays.